JavaWeb入门4.0

1. Request(请求)& Response (响应)
2. Request
- 2.1 Request 继承体系
- 2.2 Request 获取请求数据
- - 2.2.1 通用方式获取请求参数
  - 2.2.2 IDEA模板创建Servlet
  - 2.2.3 请求参数中文乱码处理
  - - 2.2.3 – I POST解决方案
    - 2.2.3 – II GET解决方案
- 2.3 Request 请求转发
3. Response
- 3.1 Response 设置响应数据功能
- 3.2 Response 完成重定向
- - 3.2.1 资源路径问题
- 3.3 Response 响应字符数据
- 3.4 Response 响应字节数据
4. Request与Response 案例
- 4.1 用户登录
- - 4.1.1 环境准备
  - 4.1.2 代码实现
- 4.2 用户注册
- 4.3 SqlSessionFactory 工具类提取

1. Request(请求)& Response (响应)

2. Request

2.1 Request 继承体系

Tomcat需要解析请求数据，封装为request对象，并且创建request对象传递到service方法中
使用request对象，查阅JavaEE API文档的 HttpServletRequest 接口

2.2 Request 获取请求数据

请求数据分为3部分：

1、请求行：

String getMethod()：获取请求方式：GET
String getContextPath()：获取虚拟目录(项目访问路径):/request-demo
StringBuffer getRequestURL():获取URL(统一资源定位符)：http://localhost:8080/request-demo/req1
String getRequestURI()：获取URI(统一资源标识符)： /request-demo/req1
String getQueryString()：获取请求参数(GET方式): username=zhangsan&password=123

案例：

@WebServlet("/req1")public class RequestDemo1 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {String method = req.getMethod();System.out.println(method);String contextPath = req.getContextPath();System.out.println(contextPath);StringBuffer url = req.getRequestURL();System.out.println(url);String uri = req.getRequestURI();System.out.println(uri);String queryString = req.getQueryString();System.out.println(queryString);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {}}

2、请求头：

String getHeader(String name)：根据请求头名称，获取值

@WebServlet("/req1")public class RequestDemo1 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {String method = req.getMethod();System.out.println(method);String contextPath = req.getContextPath();System.out.println(contextPath);StringBuffer url = req.getRequestURL();System.out.println(url);String uri = req.getRequestURI();System.out.println(uri);String queryString = req.getQueryString();System.out.println(queryString);//获取请求头：uer-getHeader：浏览器的版本信息String agent = req.getHeader("user-agent");System.out.println(agent);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {}}

3、请求体：

ServletInoutStream getInputStream()：获取字节输入流
BufferedReader getReader()：获取字符输入流

案例：
RequestDemo1类：

@WebServlet("/req1")public class RequestDemo1 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {String method = req.getMethod();System.out.println(method);String contextPath = req.getContextPath();System.out.println(contextPath);StringBuffer url = req.getRequestURL();System.out.println(url);String uri = req.getRequestURI();System.out.println(uri);String queryString = req.getQueryString();System.out.println(queryString);//获取请求头：uer-getHeader：浏览器的版本信息String agent = req.getHeader("user-agent");System.out.println(agent);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//获取post 请求体：请求参数//1.获取字符输入流BufferedReader br = req.getReader();//该流会自动关闭//2.读取数据String line = br.readLine();System.out.println(line);}}

req.html：

<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>Title</title></head><body><form action="/request_demo_war/req1" method="post"><input type="text" name="username"><input type="password" name="password"><input type="submit"></form></body></html>

2.2.1 通用方式获取请求参数

请求参数获取方式：

GET 方式：

String getQueryString()

POST 方式：

BufferedReader getReader()

思考：
GET请求方式和POST请求方式区别主要在于获取请求参数的方式不一样，是否可以提供一种统一获取请求参数的方式，从而统一doGet和doPost方法内的代码？
Map getParameterMap()：获取所有参数Map集合
String[ ] getParameterValues(String name)︰根据名称获取参数值（数组)
String getParameter(String name)：根据名称获取参数值（单个值)

案例：
RequestDemo2类：

package com.itheima.web;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.BufferedReader;import java.io.IOException;import java.util.Map;@WebServlet("/req2")public class RequestDemo2 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//get请求逻辑//System.out.println("get....");//1.获取所有参数的map集合Map<String, String[]> map = req.getParameterMap();for (String key : map.keySet()) {//比如：username:zhangsanSystem.out.print(key+":");//获取value值String[] values = map.get(key);for (String value : values) {System.out.print(value+" ");}System.out.println();}System.out.println("----------------------------");//2.根据key获取参赛值，数组String[] hobbies = req.getParameterValues("hobby");for (String hobby : hobbies) {System.out.println(hobby);}//3.根据key 获取单个参数值String username = req.getParameter("username");String password = req.getParameter("password");System.out.println(username);System.out.println(password);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//获取post 请求体：请求参数this.doGet(req,resp);//一样法典复用即可//System.out.println("post....");//////1.获取所有参数的map集合//Map map = req.getParameterMap();//for (String key : map.keySet()) {////比如：username:zhangsan//System.out.print(key+":");//////获取value值//String[] values = map.get(key);//for (String value : values) {//System.out.print(value+" ");//}//System.out.println();//}//System.out.println("----------------------------");//////2.根据key获取参赛值，数组//String[] hobbies = req.getParameterValues("hobby");//for (String hobby : hobbies) {//System.out.println(hobby);//}//////3.根据key 获取单个参数值//String username = req.getParameter("username");//String password = req.getParameter("password");//System.out.println(username);//System.out.println(password);}}

html：

<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>Title</title></head><body><form action="/request_demo_war/req2" method="get"><input type="text" name="username"><br><input type="password" name="password"><br><input type="checkbox" name="hobby" value="1">游水<input type="checkbox" name="hobby" value="2">开冲<br><input type="submit"></form></body></html>

2.2.2 IDEA模板创建Servlet

便捷创建
在设置里面的代码样式下>文件和代码模板：自定义快捷修改

2.2.3 请求参数中文乱码处理

URL编码

将字符串按照编码方式转为二进制
每个字节转为2个16进制数并在前边加上%

演示UTF编码转换：

public class URLDemo {public static void main(String[] args) throws UnsupportedEncodingException {String username = "张三";//1.URL编码String encode = URLEncoder.encode(username, "utf-8");System.out.println(encode);//2.URL编码String decode = URLDecoder.decode(encode, "utf-8");String decode2 = URLDecoder.decode(encode, "ISO-8859-1");//å¼ ä¸‰System.out.println(decode);}}

解决思路：

package com.itheima.web;import java.io.UnsupportedEncodingException;import java.net.URLDecoder;import java.net.URLEncoder;import java.nio.charset.StandardCharsets;public class URLDemo {public static void main(String[] args) throws UnsupportedEncodingException {String username = "张三";//1.URL编码String encode = URLEncoder.encode(username, "utf-8");System.out.println(encode);//2.URL编码String decode = URLDecoder.decode(encode, "ISO-8859-1");//å¼ ä¸‰System.out.println(decode);//3.转换为字节数据，编码过程byte[] bytes = decode.getBytes("ISO-8859-1");//4.将字节数组转换为字符串，解码过程String s = new String(bytes, "utf-8");System.out.println(s);}}

2.2.3 – I POST解决方案

请求参数如果存在中文数据，则会乱码
解决方案:

POST：设置输入流的编码

request.setCharacterEncoding("UTF-8");

案例：

@WebServlet("/req4")public class RequestDemo4 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1.解决乱码：POST getReader()request.setCharacterEncoding("UTF-8");//设置字符输入流的参数//2.获取usernameString username = request.getParameter("username");System.out.println(username);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

2.2.3 – II GET解决方案

@WebServlet("/req4")public class RequestDemo4 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1.解决乱码：POST getReader()request.setCharacterEncoding("UTF-8");//设置字符输入流的参数//2.获取usernameString username = request.getParameter("username");System.out.println("解决乱码前："+username);//3.GET 获取参数的方式：getQueryString//乱码原因：tomcat进行URL解码时，默认的字符集ISO-8859-1//3.1 先对乱码数据进行解码：转为字节数组//byte[] bytes = username.getBytes(StandardCharsets.ISO_8859_1);//3.2 字节数组解码username = new String(username.getBytes(StandardCharsets.ISO_8859_1),StandardCharsets.UTF_8);System.out.println("解决乱码后："+username);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

小结：

2.3 Request 请求转发

请求转发（forward）：一种在服务器内部的资源跳转方式

实现方式：

req.getRequestDispatcher("资源B路径").forward(req,resp);

案例：
RequestDemo5类：

@WebServlet("/req5")public class RequestDemo5 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("demo5...");//请求转发request.getRequestDispatcher("/req6").forward(request,response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

RequestDemo6类：

@WebServlet("/req6")public class RequestDemo6 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("Demo6....");}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

请求转发资源共享数据：使用Request对象

- void setAttribute(String name, Object o)：存储数据到request域中
- Object getAttribute(String name)：根据key，获取值
- void removeAttribute(String name)：根据key，删除该键值对

案例：

@WebServlet("/req5")public class RequestDemo5 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("demo5...");//存储数据request.setAttribute("msg","helloworld");//请求转发request.getRequestDispatcher("/req6").forward(request,response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

@WebServlet("/req6")public class RequestDemo6 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("Demo6....");//获取数据Object msg = request.getAttribute("msg");System.out.println(msg);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

请求转发的特点：

浏览器地址栏路径不发生变化
只能转发到当前服务器的内部资源
一次请求，可以在转发的资源间使用request共享数据

3. Response

3.1 Response 设置响应数据功能

响应数据分为3部分:
1、响应行:HTTP/1.1 200 oK

void setStatus(int sc)∶设置响应状态码

2、响应头: Content-Type: text/html

void setHeader(String name,String value)∶设置响应头键值对

3、响应体: head>

PrintWriter getWriter():获取字符输出流
ServletOutputStream getOutputStream():获取字节输出流

3.2 Response 完成重定向

重定向（Redirect）：一种资源跳转方式

案例：
ResponseDemo1类：

@WebServlet("/resp1")public class ResponseDemo1 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("resp1......");//重定向//1.设置响应状态码302response.setStatus(302);//2.设置响应头 Location//response.setHeader("Location","/request_demo_war/resp2"); request_demo_war为自己的启动目录//简化方式完成重定向response.sendRedirect("/request_demo_war/resp2");}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

ResponseDemo2类：

@WebServlet("/resp2")public class ResponseDemo2 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("resp2......");}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

重定向特点：
- 浏览器地址栏路径发生变化
- 可以重定向到在意位置的资源（服务器内部、外部均可)
- 两次请求，不能在多个资源使用request共享数据

对比：

3.2.1 资源路径问题

明确路径谁使用” />

例如：

@WebServlet("/resp1")public class ResponseDemo1 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("resp1......");//重定向//1.设置响应状态码302response.setStatus(302);//2.设置响应头 Location//response.setHeader("Location","/request_demo_war/resp2"); request_demo_war为自己的启动目录//简化方式完成重定向//动态获取虚拟目录String contextPath = request.getContextPath();response.sendRedirect(contextPath+"/resp2");}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

3.3 Response 响应字符数据

使用：

通过Response对象获取字符输出流

PrintWriter writer = resp.getWriter();

写数据

writer.write("aaa");

例子：

@WebServlet("/resp3")public class ResponseDemo3 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置流中文编码response.setContentType("text/html;charset=utf-8");//1.获取字符输入流PrintWriter writer = response.getWriter();//content-type 识别html标签//response.setHeader("content-type","text/html");writer.write("你吗的");writer.write("aaaa
");}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

注意:

该流不需要关闭，随着响应结束，response对象销毁，由服务器关闭
中文数据乱码:原因通过Response获取的字符输出流默认编码:ISO-8859-1

resp.setContentType("text/html;charset=utf-8");

3.4 Response 响应字节数据

使用:

通过Response对象获取字符输出流

ServletOutputStream outputStream = resp.getOutputStream();

写数据

outputStream.write(字节数据);

例子：

@WebServlet("/resp4")public class ResponseDemo4 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1.读取文件FileInputStream fis = new FileInputStream("F://常用文件夹//图片//Saved Pictures//1.jpg");//2.获取response字节输出流ServletOutputStream os = response.getOutputStream();//3.完成流的copybyte[] buff = new byte[1024];int len = 0;while ((len = fis.read(buff))!=-1){os.write(buff,0,len);}fis.close();}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

但是将来不用写完成copy流的步骤了，太麻烦，一般会采用工具类

lOUtils工具类使用
导入坐标

<dependency><groupld>commons-io</groupld><artifactld>commons-io</artifactld><versign>2.6</version></dependency>

使用：

IOUtils.copy(输入流,输出流);

例如：

4. Request与Response 案例

4.1 用户登录

4.1.1 环境准备

环境准备

静态页面：

css代码：
login

* {margin: 0;padding: 0;}html {height: 100%;width: 100%;overflow: hidden;margin: 0;padding: 0;background: url(../imgs/Desert.jpg) no-repeat 0px 0px;background-repeat: no-repeat;background-size: 100% 100%;-moz-background-size: 100% 100%;}body {display: flex;align-items: center;justify-content: center;height: 100%;}#loginDiv {width: 37%;display: flex;justify-content: center;align-items: center;height: 300px;background-color: rgba(75, 81, 95, 0.3);box-shadow: 7px 7px 17px rgba(52, 56, 66, 0.5);border-radius: 5px;}#name_trip {margin-left: 50px;color: red;}p {margin-top: 30px;margin-left: 20px;color: azure;}input {margin-left: 15px;border-radius: 5px;border-style: hidden;height: 30px;width: 140px;background-color: rgba(216, 191, 216, 0.5);outline: none;color: #f0edf3;padding-left: 10px;}#username{width: 200px;}#password{width: 202px;}.button {border-color: cornsilk;background-color: rgba(100, 149, 237, .7);color: aliceblue;border-style: hidden;border-radius: 5px;width: 100px;height: 31px;font-size: 16px;}#subDiv {text-align: center;margin-top: 30px;}#loginMsg{text-align: center;color: aliceblue;}

- register：

* {margin: 0;padding: 0;list-style-type: none;}.reg-content{padding: 30px;margin: 3px;}a, img {border: 0;}body {background-image: url("../imgs/reg_bg_min.jpg") ;text-align: center;}table {border-collapse: collapse;border-spacing: 0;}td, th {padding: 0;height: 90px;}.inputs{vertical-align: top;}.clear {clear: both;}.clear:before, .clear:after {content: "";display: table;}.clear:after {clear: both;}.form-div {background-color: rgba(255, 255, 255, 0.27);border-radius: 10px;border: 1px solid #aaa;width: 424px;margin-top: 150px;margin-left:1050px;padding: 30px 0 20px 0px;font-size: 16px;box-shadow: inset 0px 0px 10px rgba(255, 255, 255, 0.5), 0px 0px 15px rgba(75, 75, 75, 0.3);text-align: left;}.form-div input[type="text"], .form-div input[type="password"], .form-div input[type="email"] {width: 268px;margin: 10px;line-height: 20px;font-size: 16px;}.form-div input[type="checkbox"] {margin: 20px 0 20px 10px;}.form-div input[type="button"], .form-div input[type="submit"] {margin: 10px 20px 0 0;}.form-div table {margin: 0 auto;text-align: right;color: rgba(64, 64, 64, 1.00);}.form-div table img {vertical-align: middle;margin: 0 0 5px 0;}.footer {color: rgba(64, 64, 64, 1.00);font-size: 12px;margin-top: 30px;}.form-div .buttons {float: right;}input[type="text"], input[type="password"], input[type="email"] {border-radius: 8px;box-shadow: inset 0 2px 5px #eee;padding: 10px;border: 1px solid #D4D4D4;color: #333333;margin-top: 5px;}input[type="text"]:focus, input[type="password"]:focus, input[type="email"]:focus {border: 1px solid #50afeb;outline: none;}input[type="button"], input[type="submit"] {padding: 7px 15px;background-color: #3c6db0;text-align: center;border-radius: 5px;overflow: hidden;min-width: 80px;border: none;color: #FFF;box-shadow: 1px 1px 1px rgba(75, 75, 75, 0.3);}input[type="button"]:hover, input[type="submit"]:hover {background-color: #5a88c8;}input[type="button"]:active, input[type="submit"]:active {background-color: #5a88c8;}.err_msg{color: red;padding-right: 170px;}#password_err,#tel_err{padding-right: 195px;}#reg_btn{margin-right:50px; width: 285px; height: 45px; margin-top:20px;}

imgs图片

HTML部分：

login

<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>login</title><link href="css/login.css" rel="stylesheet"></head><body><div id="loginDiv"><form action="" id="form"><h1 id="loginMsg">LOGIN IN</h1><p>Username:<input id="username" name="username" type="text"></p><p>Password:<input id="password" name="password" type="password"></p><div id="subDiv"><input type="submit" class="button" value="login up"><input type="reset" class="button" value="reset"><a href="register.html">没有账号？点击注册</a></div></form></div></body></html>

register

<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>欢迎注册</title><link href="css/register.css" rel="stylesheet"></head><body><div class="form-div"><div class="reg-content"><h1>欢迎注册</h1><span>已有帐号？</span> <a href="login.html">登录</a></div><form id="reg-form" action="#" method="get"><table><tr><td>用户名</td><td class="inputs"><input name="username" type="text" id="username"><br><span id="username_err" class="err_msg" style="display: none">用户名不太受欢迎</span></td></tr><tr><td>密码</td><td class="inputs"><input name="password" type="password" id="password"><br><span id="password_err" class="err_msg" style="display: none">密码格式有误</span></td></tr></table><div class="buttons"><input value="注 册" type="submit" id="reg_btn"></div><br class="clear"></form></div></body></html>

req

<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>Title</title></head><body><form action="/request_demo_war/req4" method="get"><input type="text" name="username"><br><input type="password" name="password"><br><input type="checkbox" name="hobby" value="1">游水<input type="checkbox" name="hobby" value="2">开冲<br><input type="submit"></form></body></html>

mybatis环境：

数据库创建：
pojo下的User.java

package com.itheima.pojo;public class User {private Integer id;private String username;private String password;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", password='" + password + '\'' +'}';}}

mybatis-config.xml

<!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.dorg/dt/mybatis-3-config.dtd"><configuration><typeAliases><package name="com.itheima.pojo"/></typeAliases><environments default="development"><environment id="development"><transactionManager type="JDBC"/><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql:///db1?useSSL=false&useServerPrepStmts=true"/><property name="username" value="root"/><property name="password" value="root"/></dataSource></environment></environments><mappers><package name="com.itheima.mapper"/></mappers></configuration>

UserMapper.xml

<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.itheima.mapper.UserMapper"></mapper>

4.1.2 代码实现

核心配置文件：端口自行设置，如果端口被有的站点站了，那么后面网页登录提交后会报500错误

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.example</groupId><artifactId>request-demo</artifactId><version>1.0-SNAPSHOT</version><packaging>war</packaging><properties><maven.compiler.source>17</maven.compiler.source><maven.compiler.target>17</maven.compiler.target></properties><dependencies><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version><scope>provided</scope></dependency><dependency><groupId>commons-io</groupId><artifactId>commons-io</artifactId><version>2.6</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.5</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.30</version></dependency></dependencies><build><plugins><plugin><groupId>org.apache.tomcat.maven</groupId><artifactId>tomcat7-maven-plugin</artifactId><version>2.2</version><configuration><port>85</port></configuration></plugin></plugins></build></project>

UserMapper.java:

package com.itheima.mapper;import com.itheima.pojo.User;import org.apache.ibatis.annotations.Param;import org.apache.ibatis.annotations.Select;public interface UserMapper {/*根据用户名和密码查询用户对象 */@Select("select * from tb_user where username = #{username} and password = #{password}")User select(@Param("username") String username,@Param("password") String password);}

loginServlet：

@WebServlet("/loginServlet")public class loginServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1.接收用户名和密码String username = request.getParameter("username");String password = request.getParameter("password");//2.调用mybatis完成查询//2.1 获取SqlSessionFactory对象String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);//2.2 获取SqlSession对象SqlSession sqlSession = sqlSessionFactory.openSession();//2.3 获取MapperUserMapper userMapper = sqlSession.getMapper(UserMapper.class);//2.4 调用方法User user = userMapper.select(username, password);//2.5 释放资源sqlSession.close();//获取响应数据的字符输出流，并设置content type 防止乱码response.setContentType("text/html;charset=utf-8");PrintWriter Pwriter = response.getWriter();//3.判断user释放为nullif (user!=null){// 登录成功Pwriter.write("登录成功");}else {// 登录失败Pwriter.write("登录失败");}}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

Mavn 运行：

登录成功：

4.2 用户注册

UserMapper

package com.itheima.mapper;import com.itheima.pojo.User;import org.apache.ibatis.annotations.Insert;import org.apache.ibatis.annotations.Param;import org.apache.ibatis.annotations.Select;public interface UserMapper {/*根据用户名和密码查询用户对象 */@Select("select * from tb_user where username = #{username} and password = #{password}")User select(@Param("username") String username,@Param("password") String password);/*根据用户名查询用户对象 */@Select("select * from tb_user where username = #{username}")User selectByUsername(String username);//添加用户@Insert("insert into tb_user values(null,#{username},#{password})")void add(User user);}

registerServlet类

@WebServlet("/registerServlet")public class registerServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1.接收用户数据String username = request.getParameter("username");String password = request.getParameter("password");//封装用户对象User user = new User();user.setUsername(username);user.setPassword(password);//2. 调用mapper 根据用户名查询用户对象//2.1 获取SqlSessionFactory对象String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);//2.2 获取SqlSession对象SqlSession sqlSession = sqlSessionFactory.openSession();//2.3 获取MapperUserMapper userMapper = sqlSession.getMapper(UserMapper.class);//2.4 调用方法User u = userMapper.selectByUsername(username);//3.判断用户对象释放是否为nullif (u == null){//用户不存在，添加用户userMapper.add(user);//提交事务sqlSession.commit();//释放资源sqlSession.close();}else {//用户存在，给出提示信息response.setContentType("text/html;charset=utf-8");response.getWriter().write("用户名已存在");}}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}}

register的html

<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>欢迎注册</title><link href="css/register.css" rel="stylesheet"></head><body><div class="form-div"><div class="reg-content"><h1>欢迎注册</h1><span>已有帐号？</span> <a href="login.html">登录</a></div><form id="reg-form" action="/request-demo/registerServlet" method="post"><table><tr><td>用户名</td><td class="inputs"><input name="username" type="text" id="username"><br><span id="username_err" class="err_msg" style="display: none">用户名不太受欢迎</span></td></tr><tr><td>密码</td><td class="inputs"><input name="password" type="password" id="password"><br><span id="password_err" class="err_msg" style="display: none">密码格式有误</span></td></tr></table><div class="buttons"><input value="注 册" type="submit" id="reg_btn"></div><br class="clear"></form></div></body></html>

注册成功：

4.3 SqlSessionFactory 工具类提取

创建SqlSessionFactory代码优化

存在问题：

代码重复：工具类
SqlSessionFactory 工厂只创建一次，不要重复创建：静态代码块

案例：
在itheima下的util包创建：SqlSessionFactoryUtils类

public class SqlSessionFactoryUtils {private static SqlSessionFactory sqlSessionFactory;static {//静态代码块会随着类的加载而自动执行，且只执行一次try {String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);} catch (IOException e) {e.printStackTrace();}}public static SqlSessionFactory getSqlSessionFactory(){return sqlSessionFactory;}}

实现：

小黑子—JavaWeb：第四章 Request与Response

JavaWeb入门4.0

1. Request(请求)& Response (响应)

2. Request

2.1 Request 继承体系

2.2 Request 获取请求数据

2.2.1 通用方式获取请求参数

2.2.2 IDEA模板创建Servlet

2.2.3 请求参数中文乱码处理

2.2.3 – I POST解决方案

2.2.3 – II GET解决方案

2.3 Request 请求转发

3. Response

3.1 Response 设置响应数据功能

3.2 Response 完成重定向

3.2.1 资源路径问题

3.3 Response 响应字符数据

aaaa

3.4 Response 响应字节数据

4. Request与Response 案例

4.1 用户登录

4.1.1 环境准备

4.1.2 代码实现

4.2 用户注册

4.3 SqlSessionFactory 工具类提取

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小黑子—JavaWeb：第四章 Request与Response

JavaWeb入门4.0

1. Request(请求)& Response (响应)

2. Request

2.1 Request 继承体系

2.2 Request 获取请求数据

2.2.1 通用方式获取请求参数

2.2.2 IDEA模板创建Servlet

2.2.3 请求参数中文乱码处理

2.2.3 – I POST解决方案

2.2.3 – II GET解决方案

2.3 Request 请求转发

3. Response

3.1 Response 设置响应数据功能

3.2 Response 完成重定向

3.2.1 资源路径问题

3.3 Response 响应字符数据

aaaa

3.4 Response 响应字节数据

4. Request与Response 案例

4.1 用户登录

4.1.1 环境准备

4.1.2 代码实现

4.2 用户注册

4.3 SqlSessionFactory 工具类提取

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